| Summary: | We have undertaken studies aimed at elucidating the interrelationships existing between the seasonal modifications in endocrine status (already demonstrated by Saboureau, M., and J. Boissin. 1978. C.R. Acad. Sci. (Paris) 286D: 1479-1482) and plasma lipoprotein metabolism in the male hedgehog. During the course of these studies, we discovered that a lipoprotein comparable to human Lp[a] was a prominent component of the plasma lipoprotein spectrum in the hedgehog. This lipoprotein was present in the 1.040-1.100 g/ml density range (approximately), exhibited pre beta mobility upon agarose gel electrophoresis, and its Stokes diameter was 275 A. Its apolipoprotein moiety consisted of two proteins with molecular weights and amino acid compositions similar to those of human apoB-100 and apo[a], respectively. These two apolipoproteins were present in hedgehog Lp[a] as a complex that could be dissociated using dithiothreitol and whose stoichiometry could be 1:1. Lp[a] polymorphism due to size heterogeneity of apo[a] appeared to be present in the hedgehog as in man. The chemical composition of hedgehog Lp[a], obtained from animals bled during spring and summer, differed from that of its human counterpart in that the proportion of triglycerides was approximately three times higher in the hedgehog particle (13% vs. 4%), to the detriment of cholesteryl esters. Dissociation of the apoB:apo[a] complex has allowed us to obtain Lp[a] devoid of its specific polypeptide (Lp[a-]), a particle that retained the characteristics of Lp[a] as regards its lipid composition but whose Stokes diameter decreased by 30 to 40 A. The plasma concentration of LDL particles, defined as lipoproteins containing apoB-100 as their sole apolipoprotein constituent, was considerably lower than that of Lp[a]. These findings suggest that the hedgehog could be a unique animal model for studies regarding Lp[a] metabolism.
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